[rescue] Sun Ultra 60> 2 Gb Memory ?

[Jonathan Patschke]

On Sat, 7 May 2022, Chris Quayle wrote:

> Thanks for the replies. If you think that 2Gb is a signed 32 bit number,
> the 2Gb limit would make sense,

Memory controllers generally don't work that way.  The uppermost bits of
addresses get mapped to individual banks in ways that may be far less
flexible than we'd otherwise hope.

> Don't have a U80, but it follows on from the U60, perhaps just an
> upgrade ?.

The chassis and overall arrangement of the components differs greatly.

> May just buy 4 x 256 dimms to see what obp thinks it's looking at...

Could also ask the system handbook:

   https://dogemicrosystems.ca/pub/Sun/System_Handbook/Sun_syshbk_V4.1/Devices/Memory/MEM_Ultra_60.html

Even if it saw 4 x 256MB DIMMs, there's no way to directly address
1024MB within a 512MB bank.

-- 
Jonathan Patschke
Austin, TX
USA